[Lazare]

Well, yes. As I said, it'll be "totally fine". :)

The problem is, the submission said "collision-free". This isn't "collision-free", it's "collisions are so unlikely you don't need to worry even under extremely conservative assumptions, assuming you have a decent source of randomness". And that's good enough for me, absolutely.

But...if that's good enough, then really, any of the common UUID and UUID-like schemes will be good enough. I'm taking the submission title to mean either "guaranteed collision-free" or, failing that, as "more collision resistant than some alternatives", or maybe "guaranteed collision-free in some specific use cases". But this doesn't seem to be any of those; it's just a timestamp and enough randomness that you'll be safe under reasonable assumptions.

In short, I'm not saying "don't use this because you'll get collisions", I'm saying "even though as a practical matter you won't see any collisions, I don't think the collision free label is appropriate".

[YetAnotherNick]

Let's do some math. Assume you generate a million UUID per second. The probability of collision in a second is c=1-e^((-10^6)^2/(2*7*10^28))=-7*10^-18. The probability it will collide once in next 10 years is 1 in a billion(seconds in 10 year * c).